Solitary Wasps

Figure 1 Thread-waisted wasp with saddled-prominent caterpillar prey

August is a good time of year to observe solitary wasps.  Solitary wasps are a group of wasps that either build a small nest or a burrow or simply find hosts insects to lay their eggs in depending on the species of solitary wasp.  They do not commonly interact with other wasps. Typically they are parastic.  One sub group of solitary wasps are known as thread-waisted wasps, one of which I noticed last week moving its large cargo. 

These thread waisted wasps create a small burrow in soils and provide lepidopteran larvae for their developing young to feed on. They first paralyze their prey. This wasp, pictured in Figure 1, was lifting and moving the caterpillar in small increments.  The caterpillar is a saddled prominent larvae that can feed on birch, beech, sugar maple, oak, aspen and apple trees. Adult saddled prominent moths emerge at the end of May or early June with larvae active in June and July.

Figure 2 Adult dog-day (annual) cicada, perched on a tree truck waiting for its wings harden, emerging from its nymphal skin

Another type of solitary wasp you may see this time of year are cicada killers. Cicada killers are large, menacing-looking wasps. People are usually concerned when they appear on their properties because they look like large yellowjackets but they rarely sting people. These wasps typically dig burrows in sunny areas in sparsely vegetated, sandy soils.  Excavated soil for their burrow is seen around the entrance. These wasps parasitize cicadas (typically dog-day cicadas in the Northeast that can be around 2” long)

Figure 3 Cicada killer wasp attacking dog-day cicada

Cicadas are not seen usually but often one can hear the male cicadas in late summer making their “buzzing” sounds to attract females. Cicada killer wasps paralyzing and then move their prey to their burrow that contains an egg. Burrows are sealed and the larvae that hatch feed on the cicada(s) provided. Cicada killer larvae then pupate in their burrow and emerge the following summer timed to the emmergence of cicadas.